1. Field of the Invention
This invention relates to the formation of microelectronic devices including magnetic elements, and more particularly, to methods for patterning a magnetic cell junction and a structure used for and resulting from such methods.
2. Description of the Related Art
The following descriptions and examples are given as background only.
Recently, advancements in the use of magnetoresistive materials have progressed the development of magnetic random access memory (MRAM) devices to function as viable non-volatile memory circuits. In general, MRAM circuits exploit the electromagnetic properties of magnetoresistive materials to set and maintain information stored within individual magnetic memory cell junctions of the circuit. Typically, a magnetic cell junction is formed from patterning a stack of layers such that a structure of a given length and width may be obtained. In some cases, the patterning process may include wet etching the stack of layers. Such a technique, however, may cause some portions of the stack of layers to be undercut. Consequently, the dimensions of magnetic cell junctions formed from wet etch techniques may vary within an array. In general, variations of cell junction sizes and shapes may cause the amount of current needed to switch the magnetic direction of memory cells to vary, reducing the reliability of the memory array.
As such, in an effort to alleviate the undercut problem, dry etch techniques, such as ion milling and reactive ion etching are sometimes employed to pattern magnetic cell junctions. Such dry etch techniques, however, often cause material removed from the stack of layers to be redeposited upon sidewalls of the patterned magnetic cell junctions. In some cases, the residue may undesirably affect the operation of the ensuing circuit if not removed. In particular, the redeposition of material along the sidewalls of a magnetic cell junction may produce shorts across the tunneling barrier layer of the cell junction, prohibiting the logic state of the magnetic cell junction from being determined. In addition, residue on magnetic layers of MRAM cells may degrade the magnetic properties of the layers, reducing the reliability of the memory cells. Furthermore, residue on portions of conductive structures may undesirably increase the resistance of the structures, hindering the speed of the resulting circuit.
Therefore, it would be desirable to develop a method for patterning a magnetic cell junction with a reduced amount of residue and which does not cause layers within magnetic cell junction to be undercut or shorted. In addition, it would be advantageous to develop a method for removing residue from a topography in which a magnetic cell junction is patterned. Moreover, it would be beneficial to reduce the effect of residues on the operation of magnetic cell junctions.